462 



DISTRIBUTION OF PLANTS. 



while one slight hollow was surrounded with the golden flowers of a 

 Bidens-like Campylotheca. 



Beyond the irregular dry grassy belt, the usual lava-surflice recom- 

 menced ; with large shrubs and scraggy Metrosideros trees, rarely thirty 

 feet high, growing in a scattered manner and chiefly out of cracks. 



Our party being detained by the transportation of astronomical 

 instruments, I proceeded leisurely ; and towards sunset, reached the 

 spot selected for an encampment ; which proved the 6th from the 

 summit of the mountain. The estimated elevation was five thou- 

 sand feet ; the surface around having become a little more even, 

 with patches of soil in which grasses were growing in tufts : as the 

 last-mentioned gen. Poac. ; a Trlsetum, resembling T. airoides but 

 much larger; ?m Agrostis having the panicle coarctate ; a Paniciim, 

 near P. capillare ; and more rarely, a hairy gen. Panicoid. In the 

 cracks of the lava-surface, the grasses were replaced by trees, shrubs, 

 and certain more humble plants ; the species being the same as in the 

 vicinity of the Great Crater, and the following five abounding : the 

 Metrosideros having thick woolly leaves; a Yaccinium. ; gen. Epacrid. ; 

 the Fragaria, here only in leaf; and in somewhat arid situations, the 

 Pteris ternifoUa ?. 



The Second day, we continued ascending the black lava-streams that 

 seemed to come tumbling down upon us without end. Caves were 

 pointed out, some of them one or more miles in extent; formed appa- 

 rently by the surface of a lava-stream cooling, while the liquid portion 

 beneath continued flowing on. The inmiensity of the accumulation 

 now began to claim our attention ; as it was perceived, that the lava- 

 streams from the summit of Mauna Roa had flowed down the flanks 

 all around into the sea; excepting only in the direction of Mauna Kea, 

 as already mentioned. An hour-glass communication with the central 

 fluid of the globe has here measured time by the accumulation out- 

 side ; and the process had a beginning. What proportion of tlie accu- 

 mulation may have passed into the ocean, there are perhaps no means 

 of ascertaining; neither have careful measurements been made of the 

 mass remaining on the land ; but the elements of the problem may at 

 least be stated : To form a layer eighty miles square by a thousand 

 feet deep in sixty-four hundred years, would require an annual layer 

 one hundred miles long by one mile wide and ten feet deep. One- 

 tenth of this amount is perhaps within bounds : for from the Eruption 

 of 1832 to that of 1840, the accumulation in the Great Crater was at 



